A large number of commercial and factory or plant roofs are of a flat roof design wherein the roofing material itself is often of a built-up asphalt and, in more modern systems, of a single ply EPDM elastomeric sheet or membrane. In terms of securing a single ply EPDM membrane to the roof itself, one common design utilizes a mechanical ballast system that uses a layer of stone over the membrane. While the ballast system is least expensive, it has the disadvantage of being quite heavy (ten pounds per square foot) thus requiring a heavy roof support structure and, in addition, the roof slope cannot exceed 10.degree..
Adhered roof membrane retention systems suffer from a cost penalty while mechanical fastening systems generally require a fixation to the roofing substrate by metal fasteners with metal or rubberized nailing strips. Additional sealing strips or caps are then required to keep the punctured membrane water tight. Such installations are cumbersome as well as time-consuming in addition to violating the integrity of the membrane itself.
The prior art construction set forth in Netherlands Pat. No. 7,906,086 to Agro discloses a fixture arrangement for foil sheets for the erection of roof coverings and the like which comprises a rail with an approximately C-shaped profile. This rail has a smooth back and top and bottom grooves for a clamp frame which is flat on one side. The width of the frame is greater than the distance between the edges of the frame guide grooves in the rail and smaller or equal to the distance between the edge of the lower guide groove and the top of the uppermost guide groove.
French Pat. No. 2,263,407 to Hirota appears to disclose an apparatus for maintaining a soft sheeting member C on a structural greenhouse framework. This apparatus incorporates a substantially zig-zag spring which is positioned within a diverging channel of a retainer. The spring securely retains the flexible membrane C within this channel.
Austrian Pat. No. 216,192 to Fural appears to disclose a structure having a flexible membrane positioned thereon wherein the membrane extends over a reverse-tapered ridge and is maintained thereon by a fastening element which incorporates pivotally hinged members and a locking element wherein these members fit over the ridge and the flexible membrane.
U.S Pat. No. 4,170,810 to Peleg discloses an apparatus for securing a flexible sheet to building structures wherein, as best shown in FIG. 1, a substantially U-shaped channel member is used to receive the flexible membrane. Two engaging members are inserted into the channel member, over the flexible member, to tightly clamp the sheet against the channel member.
U.S Pat. No. 4,189,880 to Ballin discloses an apparatus for attaching a plastic film along the peripheral edge of the support frame by a spline. As best shown in FIGS. 5a and 5b, a plastic sheet is attached to a window by placing it within the channel member and after such placement a spline, preferably formed of a semi-rigid plastic material, is inserted into the channel. After insertion it forces the adjacent walls outwardly into a deformed position but once fully inserted (FIG. 5b) the member is securely held between the channel and the spline member.
U.S. Pat. No. 3,757,479 to Martinez discloses a device for holding a flexible sheet to a frame wherein the sheet is secured in a C-shaped rigid channel by a flexible and resilient strip having an initial inverted V-shape that has a longitudinal groove in its top surface. Upon installation the resilient strip is designed to assume a V-shape as it is wedged into its retaining channel.
French Pat. No. 1,467,374 to Buordelot appears to disclose a flexible strip with a groove thereon that apparently functions to facilitate entry into a rigid C-shaped channel to fixedly retain the strip therein.
U.S. Pat. No. 4,234,035 to Babbs in FIGS. 1 and 2 discloses a device for holding trim to upholstered furniture wherein a semi-rigid U-shaped member is attached to the chair and a contoured flexible strip is wedged thereinto. The strip utilizes a pair of ribs 13 that are spaced apart in order to give the strip a gap or track.
U.S. Pat. No. 3,681,887 to Loew discloses a decorative trim strip for an automobile. The strip in its natural state, i.e. before insertion into the recipient channel, appears to have a groove on the outer surface running longitudinally down the strip. Both the channel and the locking strip are composed of a flexible material.
U.S. Pat. No. 3,851,848 to Wiele discloses a device for attaching a flexible sheet to a rigid structure which can be used, for example, in awnings. The device incorporates a flexible locking strip having a groove thereon which enables a locking strip to hinge or bend inwardly.
German Patent Publication No. 2,433,669 pertains to a device for securing loosely placed roofing membranes wherein a cone-shaped base member is first attached to the roof and the membrane is secured between the base member and a top cap member yieldingly fitting into a restricted bore in the base member. A retaining member is then inserted into a central aperture of the cap member to secure the cap member to the base member.